NOTE: The first edition of Knights Under the Prophet’s Banner (which you can download here) was completed around the time of 9/11 and it was published and serialized by the Saudi newspaper Ash-Sharq al-’Awsaṭ in October 2001. Click here to see an in depth description of the first edition from Ash-Sharq al-’Awsaṭ. Also see Youssef H. Aboul-Enein’s critical review of the book here. The first edition was 252 pages while the second is 507 pages.
Click the following link for a safe PDF copy of the second edition of the book: Ayman al-Zawahiri — Knights Under the Prophet’s Banner (Second Edition)